Thursday, March 22, 2018

isolde's motor mounts

I was so sure that the motor mounts in Isolde has deteriorated badly after 28 years. A lot of chain tire shops now refuse to mount and balance your tires if they are over 10 years old which I think is another notch up with their scams. I have been told rubber will continue to vulcanize after the product is made, and soon they lose the flexibility. My experience with tires and rubber molding is the sun is their biggest enemy.

this is the engine bay of a 28 years old vehicle; everything is original

I might had change one of the belt once

the oxygen sensor connectors

 these three original bolts needs to be replaced this time - for future service sake

this is a very good muffler that was made in Poland that I bought very long time ago; today the quality are not as good and the biggest challenge is the fit (very critical); the red arrow is the motor mount load bearing cross bar which needs to be removed to get to the motor mounts

I sprayed all the exhaust bolts with WD40 the day before

it is much easier to get to the motor mount top nuts by removing this motor mount bracket that attaches to the engine

it would turn out that I had to loosen this flare joint too when re-installing the muffler

this is the flare joint for one end of the catalytic converter; the catalytic converter is original

the muffler is removed in order to allow the removal of the stainless steel heat shield above the muffler; the red arrow shows the badly corroded bolts because the tail pipe is stainless steel while the muffler flange and the bolts are steel

some of the fasteners securing the original stainless steel heat shield

the arrows shows the locations of the two stainless steel muffler support brackets

the motor mount load bearing cross bar

the coolant expansion tank must be removed to before the stainless steel heat shield may be removed

I am so glad to have this pair of spring clamp pliers making the removal and re-installation of the spring clamp easy and safe

I was expecting the 4 motor mounts to be in very bad shape. I thought the steel brackets must have delaminated from the rubber block. Amazingly the rubber has no visual sign of deterioration after 28 years.

the original and new motor mount side by side; the surface cracks are from whatever coating or mold release compound; these are the outer mounts with a hook shape bend to restrain the motor from being lifted off the mount (tensile load as opposed to the normal compression load)

the inner mounts

The reason that I went to such length to replace the motor mount not knowing their condition is you cannot inspect their condition until you remove them. They are hidden out of view because of the flat four engine configuration that morphed from the original air cooled to water cooled over the decades.

the red arrows are the motor mounts after the cross bar is removed

after the installation of the new motor mounts it turns out I would spent many hours struggle to re-align the many joints of the exhaust system; each of the fasteners is a struggle and all the brackets and flanges have to be just right to not put stress on the cylinder heads

Just to be sure I have a good handle of the conditions of the 28 years old motor mounts I clamped each into the vice and flex the rubbers. I cannot find any sign of deterioration or delamination where the rubber block bounds to the steel plates. These German made rubber mounts sure are very impressive.

these 28 years old motor mounts are almost as good as new - I am so shocked


  1. Ozone along with sun does the most damage to rubber. It attacks the carbon double bonds in the molecules like the UV light does. The PNW is pretty low in ozone compared to CA.

    1. Nice to know, Mr. Chemistry. I was stellar with physics but I hate organic chemistry. The day that I found out I made the last organic chemistry course I was so relieved that I would never ever need to remember those strange chained C, H, O thingies again. Too much like prison chain-gangs.